The primary aim of the proposed research is to demonstrate that promoting a normoglycemic intrauterine milieu in women with gestational diabetes (GDM) diagnosed in the first trimester of pregnancy by the International Association of Diabetes in Pregnancy Study Groups (IADPSG) criteria (fasting plasma glucose (FPG) 92-125 mg/dL) will decrease the accumulation of fetal white adipose tissue and development of infant/child obesity during the first year of life. This project: Treating First Trimester Gestatioal Diabetes: A Randomized Controlled Trial is built upon the hypothesis that pregnant subjects with GDM randomized in the first trimester of pregnancy to strict glycemic control and pharmacotherapy as needed will have less fetal adiposity and adverse neonatal outcomes than those who receive the diagnosis of GDM but do not initiate care until the third trimester. In the proposed study, 280 women meeting the above criteria for GDM at d 15w0d gestation will be randomized to either first trimester or third trimester treatment. Each group will have diabetes education, initiate blood glucose monitoring, begin pharmacotherapy as needed (per established protocol), undergo growth ultrasounds, and antenatal testing. The first trimester arm will receive the above interventions immediately upon diagnosis of GDM whereas the third trimester arm will receive only routine prenatal care until 28 weeks at which time they will begin education and treatment. Both groups will be treated identically from 28 weeks until delivery. The primary outcome, neonatal fat mass will be calculated based on length, weight, and skinfold thickness within 48 hours of delivery. Additionally, neonates born to mothers in both arms will be followed for 12 months after delivery in order to determine if weight-for-length differs between first trimester and third trimester treatment of GDM. Our secondary outcome will be adherence to the Institute of Medicine guidelines for gestational weight gain. In the 2013 NIH/NICHD GDM Consensus Conference, the panel was concerned about adopting criteria that would increase prevalence of GDM (i.e. first trimester treatment) without first demonstrating improved outcomes. The results of this proposed trial, utilizing the IADPSG paradigm, will allow us to fill key research gaps; this is the first prospective trial to evaluate the IADPSG recommendations for screening and diagnosing GDM in the first trimester. Findings from this research will quantify the maternal and neonatal benefits and harms of treating women with GDM from early pregnancy. Additionally, the cohort of neonates that will result from this study can be followed into childhood to evaluate whether first trimester treatment has benefits beyond those anticipated at birth and may decrease the long-term incidence of obesity and diabetes.